1. Technical Field
The present invention relates to a throttle assembly for controlling the flow (amount of the flow) of intake air in an internal combustion engine, as well as a throttle sensor for detecting the degree of opening of a throttle valve used in the throttle device.
2. Background Art
Heretofore, an electronically controlled throttle assembly has practically been used wherein the operation of a throttle valve in an engine is controlled by an electrically-driven actuator (e.g., a DC motor or a stepping motor).
The electronically controlled throttle assembly controls the throttle valve angle (throttle valve opening) to an optimum value according to the state of an engine and in accordance with a signal indicative of the degree of opening of an accelerator pedal or a traction control signal. To this end, a sensor for detecting the angle of the throttle valve, what is called a throttle sensor (also called an opening meter or a throttle position sensor) is attached to a throttle body.
As the throttle sensor there generally is adopted a potentiometer type sensor, wherein a brush (slider) adapted to rotate together with a throttle valve shaft slides on a resistor, thereby outputting a potential difference signal (sensor detection signal) corresponding to the degree of opening of a throttle valve.
As throttle sensors of this type so far used there are known, for example, such throttle sensors as are disclosed in Japanese Patent Laid Open Nos. 7-343878 and 9-32588, wherein a resistor and a wiring pattern of a potentiometer are formed on a substrate. The substrate is attached to a cover of a receptacle portion containing a reduction gear mechanism. A brush is attached to a flat surface of a driven gear (or a rotor) mounted on a throttle valve shaft. In this type of a throttle sensor, the brush slides on a resistor and a conductor both formed on the substrate (a flat surface). Since the driven gear is used also as a moving element to which the brush of the potentiometer is attached, the number of components used can be so much reduced.